The aim of the proposed research is to study RNA polymerase from chicken myeloblastosis leukemia and normal chicken bone marrow cells and then to use this experience to isolate, purify and characterize RNA polymerase from human leukemia cells and normal human leukocytes. The ultimate goal of this research is to see if it is possible to arrest neoplastic expression at the transcriptional level by selectively inhibiting a leukemia-specific RNA polymerase. Comparison of the isolated RNA polymerases of leukemia and normal cells will include study of the properties, localization, functions, subunit structures and RNA product analysis of these polymerases and to purify and characterize the stimulation factors. Inhibitor studies will include determination of the effect of several presently available as well as newer experimental anti-leukemic drugs on in vitro RNA synthesis with particular regard for drugs which may selectively inhibit the malignant RNA polymerase without affecting the normal enzyme.